The Mozilla Maintenance Service can be invoked by an unprivileged user to overwrite arbitrary files with junk data using the Mozilla Windows Updater, which runs with the Maintenance Service's privileged access. Note: This attack requires local system access and only affects Windows. Other operating systems are not affected. This vulnerability affects Firefox ESR < 52.2 and Firefox < 54.
https://www.mozilla.org/security/advisories/mfsa2017-16/
https://www.mozilla.org/security/advisories/mfsa2017-15/
https://bugzilla.mozilla.org/show_bug.cgi?id=1336964